More than a million older Americans with heart failure experience high mortality, disabling symptoms, loss of independence, depression and repeated hospitalizations. Care of these patients is complex, challenging and often inadequate. New models of physician-advanced practice nurse (APN) co-management of elders during an acute episode of heart failure and extending from hospital to home have demonstrated promise in improving patient outcomes and reducing costs of care. However, the mechanisms that contribute to effectiveness of these new models of care are not well understood. Nor is it clear how care delivered by physician-APN teams differs from traditional care models. The major objective of this study is to examine differences in processes and outcomes of alternative models of physician-nurse co-management among older adults with acute heart failure. This study will compare four physician-nurse models for co-managing elders during an exacerbation of heart failure: a) in the use of evidence-based practice (care process); b) on the primary outcomes of quality life and rehospitalization; and c) for relationships among the use of evidence-based practice, the primary outcomes (quality life and rehospitalization) and intermediary variables (patient adherence with prescribed diet, medications and activity; adverse clinical events; access to health services; functional status; depression; subjective health rating and patient satisfaction). The study also will identify patient, caregiver, environmental, provider and health system factors that facilitate or interfere with or impede physician-nurse co-management. Clinical, sociodemographic and economic data collected during an on-going NINR-funded multi-center RCT will be supplemented by collection and analysis of an enriched set of process and outcomes data on study subjects (N=250). This knowledge is required to inform the design of patient care management models for the growing population of high-risk complex, elderly patients. Study findings will guide future efforts to measure adherence by provider teams to evidence-based practice and to link providers' adherence with patient outcomes. Findings from the exploratory analyses will advance understanding of the range and complexity of factors that influence outcomes and help explain the observed heterogeneity in patient outcomes following APN interventions. This study thus will facilitate development in an increasingly cost-constrained environment of high quality, targeted effective and efficient interventions to improve health for high-risk elderly patients with complex health needs.